Hello Durangomomma,
Can you tell me the Android version that is in your phone? I had thought that the S6 was coming out with Lollipop (5.x) which I have seen as an update in the Note 3 & S5, with that update Samsung did finally step up and fix the issue on their side. However I would still suggest having this TSB performed because there are a couple other enhancements that were made for network related issues.
To answer your question, yes I do believe that it will cure the issue. I'll see if I can find a friend that has rec'd the S6 and test it though just for my own satisfaction of knowing for sure. I thought that they were only a prepay unit and didn't know they were available already.